A well known example is the mule - a sterile hybrid between the donkey and the horse. It is useful for carrying heavy loads but is a reproductive dead-end.

A team of researchers from Panama, Colombia and the UK managed to recreate Heliconius heurippa in the laboratory by crossing two other species of butterfly; Heliconius cydno and Heliconius melpomene.

"The fact we've recreated this species in the lab provides a pretty convincing route by which the natural species came about," co-author Chris Jiggins, of the University of Edinburgh, told BBC News.

Jesus Mavarez, another author from the Smithsonian Tropical Research Institute in Panama, explained: "We found that a wing pattern almost identical to that of the hybrid can be obtained in months - just three generations of lab crosses between H. cydno and H. melpomene.

Wing patterns

"Moreover, natural hybrids from San Cristobal, Venezuela, show wing patterns very similar to H. heurippa, further supporting the idea of a hybrid origin for this species."

In addition, there is growing circumstantial evidence for hybrid speciation in Ragoletis fruit flies, swordtail fish and African cichlid fish.

Some also suspect the American red wolf could be the product of hybridisation between coyotes and wolves.

Colour patterns on the wings of the butterflies may be crucial in forming new species, because they serve as mating cues. These butterflies are extremely choosey about finding mates with their own, species-specific wing pattern.

The wing patterns of H. heurippa individuals make them undesirable as mates for members of their parent species, but attractive to each other - reinforcing patterns of mating that lead to a new species.

These species-specific patterns are also crucial in deterring predators. The butterflies produce toxins when eaten and predators learn to recognise and avoid a specific wing pattern.

This is so finely tuned that butterflies with even slight deviations in colour pattern suffer from higher predation.